Extra-Oral Sinus Investigation — ORE Part 1 MCQ

Instant feedback + full explanation. One question, done properly.

ModerateEndodonticsExtra-Oral Sinus InvestigationORE Part 1

A patient undergoing endodontic retreatment has a persistent extra-oral sinus tract draining through the skin of the submandibular region. Which investigation is most appropriate to identify its source?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Place a gutta-percha point in the tract and take a periapical radiograph

A is correct. A sinus tract should be traced by inserting a gutta-percha point into its opening and taking a periapical radiograph. This delineates the tract and identifies the associated tooth or periradicular lesion, which is particularly important when drainage persists during retreatment. A tract swab may grow colonising organisms but does not establish the dental source. Biopsy or cutaneous surgery is not first-line when an odontogenic sinus is suspected and risks treating the manifestation rather than the cause. Ultrasound may define soft-tissue anatomy but is not the standard investigation for tracing an odontogenic sinus. Antibiotics alone neither identify nor remove the underlying endodontic cause.

Reference: Royal College of Surgeons of England, Faculty of Dental Surgery. Guidelines for Surgical Endodontics, Radiological assessment, 2012. https://www.rcseng.ac.uk/-/media/files/rcs/fds/publications/surgical_endodontics_2012.pdf